Sección especial: Espacios, relaciones sociales y poder. Propuestas para estudiarlos Juan Manuel Tornello Notificaciones, reel, noticieros, streaming, tweets invaden permanentemente nuestra atención. Hay una saturación de datos, muchas veces contradictorios, donde se mezcla sin mucha jerarquía un muestrario de hechos relevantes e irrelevantes. Los algoritmos nos seccionan y seleccionan en función de preferencias.
We prove the consistency of the inequality $\mathfrak{r}_{\mathsf{nwd}}<\mathfrak{irr}$, which in turn implies the consistency of $\mathfrak{r}_\mathsf{nwd}<\mathfrak{i}$ and $\mathfrak{r}_{\mathsf{scatt}}<\mathfrak{irr}$. This answers one question from \cite{balzar_hrusak_hernandez} and one question from \cite{cancino_irresolvable_1}. We also prove the consistency of the inequality $\mathfrak{r}_\mathbb{Q}<\mathfrak{u}_\mathbb{Q}$.
This note shows how recent work of Eskew and Hayut can be combined with a method of Raghavan and Shelah to show the consistency of $\mathfrak u_κ<2^κ$ for $\aleph_3\leq κ<\aleph_ω$, from a huge cardinal.
In this note, we provide a proof of a technical result of Erdős and Hajnal about the existence of disjoint type graphs with no odd cycles. We also prove that this result is sharp in a certain sense.
We have provided a pure model-theoretic proof for the decidability of the additive structure of the integers together with the function {f} sending {x} to {[φx]} where φ is the golden ratio.
We show that large sets in Ellentuck topology (i.e. sets which are not nowhere Ramsey) do not admit Kuratowski's partition. The similar result is true for the Sacks real forcing.
Analytic concepts contribute to our understanding of randomness of reals via algorithmic tests. They also influence the interplay between randomness and lowness notions. We provide a survey, written on the occasion of Rod Downey's 60th birthday.
We formulate a Hilbert-style axiomatic system for STIT logic of imagination recently proposed by H. Wansing and prove its completeness by the method of canonical models.
In this paper we show that every locally finite quasivariety of MV-algebras is finitely generated and finitely based. To see this result we study critical MV-algebras. We also give axiomatizations of some of these quasivarieties.
In this paper, we introduce the concept of several products of rough finite state machines. We establish their relationships through coverings and investigate some algebraic properties for these products.
We clarify the relationship between unimodulariy in the sense of Hrushovski and measurability in the sense of Macpherson and Steinhorn, correcting some statements in the literature. In particular we point out that the notions coincide for strongly minimal sets.
Assuming Jensen's principle diamond-plus we construct Souslin algebras all of whose maximal chains are pairwise isomorphic as total orders, thereby answering questions of Koppelberg and Todorcevic
I show that assuming PFA, every proper Scott set is the standard system of a model of PA. A Scott set X is proper if it is arithmetically closed and the quotient Boolean algebra X/Fin is a proper partial order.
A set of reals A is called perfectly meager if A \cap P is meager in P, for every perfect set P. Marczewski asked if the product of perfectly meager sets is perfectly meager. In the paper it is shown that it is consistent that the answer to this question is positive. (It is known that it is also consistent that the answer is negative (Reclaw))
It is shown that if every projective set of reals is Lebesgue measurable and has the property of Baire, if every projective set in the plane has a projective uniformization, and if Steel's K exists, then J^K_{ω_1} \models "there are infinitely many strong cardinals." This is best possible, by a recent result of Steel.